The present invention relates to a motor-driven pump with a plurality of impellers.
A motor-driven pump of this type is used to increase a discharge amount of fluid discharged therefrom and known from, for example, Japanese Patent Application KOKAI Publication No. 58-8295.
The motor driven pump described in the Publication No. 58-8295 comprises an electric motor and a pump unit having a rotational center shaft coupled to the output shaft of the electric motor. Both end portions of the rotational center shaft of the pump unit are rotatably supported by both side walls of a pump housing through a pair of bearings, and a pair of impellers are fixed to a central portion of the center shaft in its longitudinal direction. The paired impellers have a pair of fluid inlet regions opening toward the both end portions of the central shaft from the neighborhood of the longitudinal center portion of the rotational center shaft in an inner space of the pump housing, and one fluid discharge region opening outward in a radial direction of the rotational center shaft from the neighborhood of the central portion. Namely, in the paired impellers, a pair of fluid channels from the paired fluid inlet regions toward the one fluid discharge region are joined together in the vicinity of the fluid discharge region. In the pump housing, a spiral shaped chamber is formed in a portion facing the fluid discharge region of the paired impellers. An outlet of the spiral shaped chamber is connected to a conduit, not shown, and a distal end of this conduit reaches a position to which fluid is to be moved by this motor-driven pump. In addition, in the inner space of the pump housing, fluid to be moved by this motor-driven pump is flowed into on the both side portions of the paired impellers through conduits not shown.
In case of the conventional motor-driven pump described above, when the rotational center shaft is rotated in a predetermined direction by the output shaft of the motor, the fluid in the paired fluid inlet regions of the paired impellers are given kinetic energy by a centrifugal force and are directed toward the one fluid discharge region through the paired fluid channels and further toward the position to which the fluid is to be moved by this motor driven pump through the spiral shaped chamber and the conduit, not shown, of the pump housing. At the same time, fluid on the both side portions of the paired impellers in the inner space of the pump housing is sucked into the paired fluid inlet regions of the paired impellers.
In case of the above-described conventional motor-driven pump, a pair of fluid flows from the paired fluid inlet regions toward the one fluid discharge region through the paired fluid channels in the paired impellers collide against each other at a joint point of the paired fluid channels in the vicinity of the fluid discharge region. As a result, a joined fluid flow at the joint point applies the paired impellers with a force, which varies in a direction along the rotational center shaft and applies the rotational center shaft with a varying thrust force. Besides, if the discharge amount and discharge pressure of the fluid discharged from the motor-driven pump increase, the thrust force thereof is intensified accordingly.
For these reasons, in case of the conventional motor-driven pump described above, one of the bearings is a radial bearing and the other is a radial-thrust bearing. The thrust bearing disadvantageously complicates a constitution of the pump unit, increases an outside dimension thereof, and increases its weight and manufacturing cost thereof.
The present invention has been derived from these circumstances. It is, therefore, an object of the present invention to provide a motor-driven pump having a plurality of impellers, capable of dispensing with a thrust bearing for a high thrust force, simple in constitution, small in outer dimension, small in weight and low in manufacturing cost.
To achieve the above object, a motor-driven pump with a plurality of impellers according to the present invention, comprises:
an electric motor including an output shaft, a motor frame rotatably supporting the output shaft while at least one end portion of the output shaft is protruded outward, and a rotation driving mechanism provided in the motor frame and rotating the output shaft in a predetermined direction when the mechanism is supplied with electric power;
a pump housing provided on a side of the one end portion of the output shaft in the electric motor, having two fluid inlet port regions on a side near the electric motor and on a side away from the electric motor in a longitudinal direction of the output shaft, respectively, and having one fluid discharge port region between the two fluid inlet port regions; and
an impeller unit including a pair of impellers having a partition wall concentrically fixed to the one end portion of the output shaft in an inner space of the pump housing, directing to the one fluid discharge port region, spreading outward in a radial direction of the output shaft and partitioning the inner space into a portion near the electric motor and a portion away from the electric motor, and a pair of blade means provided on both sides of the partition wall, respectively, the impeller unit moving fluid on the both sides of the partition wall from inside to outside in the radial direction along the pair of blade means of the pair of impellers by a centrifugal force in the inner space when the impeller unit is rotated by the output shaft of the electric motor in the predetermined direction.
With this constitution, while the fluids on the both sides of the partition wall are moved from inside to outside in the radial direction of the output shaft by the pair of blade means on the both sides of the partition wall in the inner space of the pump housing and reach the one fluid discharge port region of the pump housing, the fluids on both sides are separated from each other by the partition wall. Accordingly, the fluids moved as stated above are not mixed with each other on the both sides of the partition wall, and thrust forces applied to the impeller unit by the fluids moved on the both sides of the partition wall as stated above, does not vary. Then, it is possible to set that the fluids moved on the both sides of the partition wall as stated above always mutually cancel the thrust forces applied to the impeller unit.
Due to this, the motor-driven pump with a plurality of impellers according to the present invention dispenses with a thrust bearing for a high thrust force, is simple in constitution, small in outer dimension, small in weight and low in manufacturing cost.
In the motor-driven pump with a plurality of impellers according to the invention constituted as described above, a radial bearing rotatably supporting the other end portion of the output shaft can be provided in an opposite portion to the pump housing in the motor frame of the electric motor; and another radial bearing rotatably supporting the one end portion of the output shaft can be provided in a portion adjacent the pump housing in the motor frame of the electric motor.
Alternatively, a radial bearing rotatably supporting the other end portion of the output shaft can be provided in an opposite portion to the pump housing in the motor frame of the electric motor; and another radial bearing rotatably supporting the one end portion of the output shaft can be provided in a portion, located outward from the one end portion in the longitudinal direction of the output shaft, in the pump housing of the electric motor.
In the motor-driven pump according to the invention constituted as described above, in the pump housing, the fluid inlet port region on the side away from the electric motor can open outward in the longitudinal direction of the one end portion of the output shaft; and in the pump housing, the fluid inlet port region on the side adjacent the electric motor can open outward in the radial direction of the output shaft.
In this case, it is preferable that the one fluid discharge port region of the pump housing has a plurality of fluid discharge ports; and that the plurality of fluid discharge ports are arranged equidistantly in a circumferential direction of the one end portion of the output shaft.
If so, it is possible to set that fluids discharged from the plurality of fluid discharge ports of the fluid discharge port region can mutually cancel radial forces applied to the impeller unit in the radial direction of the output shaft. Due to this, it is possible to make a constitution of the radial bearing small in size and to further reduce its outside dimension and price of the motor-driven pump according to the present invention.
The extending ends of the plurality of fluid discharge ports can be integrated into one end.
To achieve the above object, another motor-driven pump with a plurality of impellers according to the present invention, comprises:
an electric motor including an output shaft, a motor frame rotatably supporting the output shaft while at least one end portion of the output shaft is protruded outward, and a rotation driving mechanism provided in the motor frame and rotating the output shaft in a predetermined direction when the mechanism is supplied with electric power;
a pump housing provided on a side of the one end portion of the output shaft in the electric motor, having two fluid inlet port regions on a side near the electric motor and on a side away from the electric motor in a longitudinal direction of the output shaft, respectively, and having one fluid discharge port region between the two fluid inlet port regions; and
an impeller unit including a pair of impellers having a partition wall concentrically fixed to the one end portion of the output shaft in an inner space of the pump housing, directing to the one fluid discharge port region, spreading outward in a radial direction of the output shaft and partitioning the inner space into a portion near the electric motor and a portion away from the electric motor, and a pair of blade means provided on both sides of the partition wall, respectively, the impeller unit moving fluid on the both sides of the partition wall from inside to outside in the radial direction along the pair of blade means of the pair of impellers by a centrifugal force in the inner space when the impeller unit is rotated by the output shaft of the electric motor in the predetermined direction, and wherein
an inner space penetrated by the output shaft is provided in the motor frame of the electric motor;
the motor frame further includes a pump housing communication port region for communicating the inner space with the one fluid inlet port region located at the side near the electric motor in the pump housing, and an external communication port region for communicating the inner space with an outer space of the motor frame on the side farther from the pump housing than the pump housing communication port region in the longitudinal direction of the output shaft;
the outer space is filled with fluid; and
the electric motor includes an axial-flow impeller unit, provided at the output shaft in the inner space, for moving the fluid in the inner space toward the pump housing communication port region along the longitudinal direction of the output shaft by the rotation of the output shaft in the predetermined direction.
With this constitution, while the fluids on the both sides of the partition wall are moved from inward to outward in the radial direction of the output shaft by the pair of blade means on the both sides of the partition wall in the inner space of the pump housing and reach the one fluid discharge port region of the pump housing, the fluids on both sides are separated from each other by the partition wall. Accordingly, the fluids moved as stated above are not mixed with each other on the both sides of the partition wall, and thrust forces applied to the impeller unit by the fluids moved on the both sides of the partition wall as stated above, does not vary. Then, it is possible to set that the fluids moved on the both sides of the partition wall as stated above always mutually cancel the thrust forces applied to the impeller unit.
Due to this, another motor-driven pump with a plurality of impellers described above and according to the present invention dispenses with a thrust bearing for a high thrust force, is simple in constitution, small in outer dimension, small in weight and low in production cost.
Moreover, according to this invention, fluid can be supplied to the electric motor side on the partition wall in the inner space of the pump housing by the axial-flow impeller unit of the electric motor. Therefore, this invention can reduce a capacity of the electric motor side on the partition wall in the inner space of the pump housing and reduce the dimension of the pump housing in the direction along the output shaft (i.e., the dimension of the motor-driven motor of this invention in the above direction) without deteriorating the performance of the motor-driven pump according to this invention such as discharge amount and discharge pressure of fluid discharged therefrom.
In another motor-driven pump described above and according to this invention, a radial bearing rotatably supporting the other end portion of the output shaft can be provided in an opposite portion to the pump housing in the motor frame of the electric motor; and another radial bearing rotatably supporting the one end portion of the output shaft can be provided in a portion adjacent the pump housing in the motor frame of the electric motor.
In addition, it is preferable that the rotation driving mechanism of the electric motor includes a rotor fixed to the output shaft in the inner space of the motor frame, and a stator opposite to the rotor in a radial direction of the output shaft in the motor frame; a concave portion elongated in the longitudinal direction of the rotor is formed on an outer peripheral surface of the rotor, a circumferential position of the concave portion deviated while extending in the longitudinal direction of the output shaft; and the rotor having the concave portion constitutes the axial-flow impeller unit.
The axial-flow impeller unit thus constituted is simple and compact in constitution and easy to manufacture.
In another motor-driven pump described above and according to this invention, it is preferable that in the pump housing, the fluid inlet port region on the side away from the electric motor opens outward in the longitudinal direction of the one end portion of the output shaft; and that in the pump housing, the fluid inlet port region on the side adjacent the electric motor opens toward the electric motor in the longitudinal direction of the output shaft.
The axial-flow impeller unit can efficiently feed fluid into the fluid inlet port region in such a pump housing from the pump housing communication port region of the motor frame of the electric motor.
In another motor-driven pump described above and according to this invention, it is preferable that the one fluid discharge port region of the pump housing has a plurality of fluid discharge ports; and the plurality of fluid discharge ports are arranged equidistantly in a circumferential direction of the one end portion of the output shaft.
If so, it is possible to set that fluids discharged from the plurality of fluid discharge ports of the fluid discharge port region can mutually cancel radial forces applied to the impeller unit in the radial direction of the output shaft. Due to this, it is possible to make the constitution of the radial bearing small in size and to further reduce the outside dimension and price of the motor-driven pump according to the present invention.
The extending ends of the plurality of fluid discharge ports can be integrated into one end.
In another motor-driven pump described above and according to this invention, it is preferable that a portion adjacent the pump housing around the output shaft and exposed to the pump housing communication port region in the motor frame is inclined inward in the radial direction of the output shaft as the portion is closer to the partition wall of the impeller unit.
If so, the axial-flow impeller unit can efficiently feed fluid into the fluid inlet port region in such a pump housing from the pump housing communication port region of the motor frame of the electric motor.
In another motor-driven pump described above and according to this invention stated above, a radial bearing rotatably supporting the other end portion of the output shaft can be provided in an opposite portion to the pump housing in the motor frame of the electric motor; and another radial bearing rotatably supporting the one end portion of the output shaft can be provided in a portion, located outward from the one end portion in the longitudinal direction of the output shaft, in the pump housing of the electric motor.
In this case, if the rotation driving mechanism of the electric motor includes a rotor fixed to the output shaft in the inner space of the motor frame, and a stator opposite to the rotor outward in the radial direction of the output shaft in the motor frame, a concave portion elongated in the longitudinal direction of the rotor is formed on an outer peripheral surface of the rotor, a circumferential position of the concave portion deviated while extending in the longitudinal direction of the output shaft and the rotator having the concave portion constitutes the axial-flow impeller unit, then it is preferable that a portion of the rotor adjacent the pump housing around the output shaft is exposed to the pump housing communication port region of the motor frame, and inclined inward in the radial direction of the output shaft as the portion is closer to the partition wall of the impeller unit.
Since the portion of the rotor adjacent the pump housing around the output shaft is inclined as stated above, the axial-flow impeller unit can efficiently feed fluid into the fluid inlet port region in such a pump housing fluid from the pump housing communication port region of the motor frame of the electric motor.
To achieve the above object, yet another motor-driven pump with a plurality of impellers according to the present invention, comprises:
an electric motor including an output shaft, a motor frame rotatably supporting the output shaft while at least one end portion of the output shaft is protruded outward, and a rotation driving mechanism provided in the motor frame and rotating the output shaft in a predetermined direction when the mechanism is supplied with electric power;
a pump housing provided on a side of the one end portion of the output shaft in the electric motor, having two fluid inlet port regions on a side near the electric motor and on a side away from the electric motor in a longitudinal direction of the output shaft, respectively, and having one fluid discharge port region between the two fluid inlet port regions; and
an impeller unit including an impeller having a partition wall concentrically fixed to the one end portion of the output shaft in an inner space of the pump housing, directing to the one fluid discharge port region, spreading outward in a radial direction of the output shaft and partitioning the inner space into a portion near the electric motor and a portion away from the electric motor, and a blade means provided on a side away from the electric motor on the partition wall, the impeller unit moving fluid on the side away from the electric motor on the partition wall from inside to outside in the radial direction along the blade means of the impeller by a centrifugal force in the inner space when the impeller unit is rotated by the output shaft of the electric motor in the predetermined direction, and wherein
an inner space penetrated by the output shaft is provided in the motor frame of the electric motor;
the motor frame further includes a pump housing communication port region for communicating the inner space of the motor frame with the one fluid inlet port region located at the side near the electric motor it the pump housing, and an external communication port region for communicating the inner space of the motor frame with an outer space of the motor frame on the side farther from the pump housing than the pump housing communication port region in the longitudinal direction of the output shaft;
the outer space is filled with fluid; and
the electric motor includes an axial-flow impeller unit, provided at the output shaft in the inner space, for moving the fluid in the inner space toward the pump housing communication port region along the longitudinal direction of the output shaft by the rotation of the output shaft in the predetermined direction.
With this constitution, while the fluids on the both sides of the partition wall are moved from inward to outward in the radial direction of the output shaft by the blade means on one side of the partition wall and by the axial-flow impeller unit of the electric motor in the inner space of the motor frame and reach the one fluid discharge port region of the pump housing, the fluids on both sides are separated from each other by the partition wall. Accordingly, the fluids moved as stated above are not mixed with each other on the both sides of the partition wall, and thrust forces applied to the impeller unit by the fluids moved on the both sides of the partition wall as stated above, does not vary. Then, it is possible to set that the fluids moved on the both sides of the partition wall as stated above always mutually cancel the thrust forces applied to the impeller unit.
Due to this, yet another motor-driven pump with a plurality of impellers described above and according to the present invention dispenses with a thrust bearing for a high thrust force, is simple in constitution, small in outer dimension, small in weight and low in production cost.
Moreover, according to this invention, the fluid can be supplied to the electric motor side on the partition wall in the inner space of the pump housing by the axial-flow impeller unit of the electric motor. Therefore, this invention can reduce a capacity of the electric motor side on the partition wall in the inner space of the pump housing, and further, since the blade means is not provided on the electric motor side on the partition wall, this invention can reduce the dimension of the pump housing in the direction along the output shaft (i.e., the dimension of the motor-driven motor of this invention in the above direction), without deteriorating the performance of the motor-driven pump according to this invention such as discharge amount and discharge pressure of fluid discharged therefrom or even if the performance is to be improved.
In yet another motor-driven pump described above, a radial bearing rotatably supporting the other end portion of the output shaft can be provided in an opposite portion to the pump housing in the motor frame of the electric motor; and another radial bearing rotatably supporting the one end portion of the output shaft can be provided in a portion, located outward from the one end portion of the output shaft in the longitudinal direction in the pump housing.
In this case, it is preferable that the rotation driving mechanism of the electric motor includes a rotor fixed to the output shaft in the inner space of the motor frame, and a stator opposite to the rotor in a radial direction of the output shaft in the motor frame; a concave portion elongated in the longitudinal. direction of the rotor is formed on an outer peripheral surface of the rotor, a circumferential position of the concave portion deviated while extending to the longitudinal direction of the output shaft; and the rotor having the concave portion constitutes the axial-flow impeller unit.
The axial-flow impeller unit thus constituted is simple and compact in constitution and easy to manufacture.
If a portion of the rotor adjacent the pump housing around the output shaft is exposed to the pump housing communication port region of the motor frame and is abutted against a side of the electric motor of the partition wall of the axial-flow impeller unit, it is possible to more efficiently flow the fluid from the axial-flow impeller unit into the pump housing through the pump housing communication port region of the motor frame.
In yet another motor-driven pump stated above, it is preferable that in the pump housing, the fluid inlet port region on the side away from the electric motor opens outward in the longitudinal direction of the one end portion of the output shaft; and that in the pump housing, the fluid inlet port region on the side adjacent the electric motor opens toward the electric motor in the longitudinal direction of the output shaft.
If so, the axial-flow impeller unit can efficiently feed fluid into the fluid inlet port region of the pump housing from the pump housing communication port region of the motor frame of the electric motor.
If the one fluid discharge port region of the pump housing has a plurality of fluid discharge ports, and the plurality of fluid discharge ports are arranged equidistantly in a circumferential direction of the one end portion of the output shaft, this can reduce the radial forces applied to the output shaft and reduce the outer dimension and manufacturing cost of yet another motor-driven pump according to this invention as stated above in the case of the motor-driven pump according to this invention and another motor-driven pump according to this invention.
Needless to say, the extending ends of the plurality of fluid discharge ports can be integrated into one end.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.